Wood stoves are being used increasingly for space heating. Creosote formed from incomplete combustion of the wood causes chimney fires and also air pollution. When the chimney is cool, creosote condenses in the chimney. Later, when the chimney becomes hot, the deposit of creosote can ignite and cause a chimney fire.
Catalytic burners are being installed in wood stoves to burn the creosote before it enters the chimney. Catalytic burners known in the art comprise a ceramic honeycomb coated with catalyst. These honeycombs are similar to those used in catalytic mufflers in automobiles, except that they have larger channels. The term "honeycomb" is used to indicate a structure having channels with not only hexagonal cross sections, but also square or rectangular cross sections, or indeed any arrangement wherein the catalyst support is not a continuous slot from side to side. If the mouth of a rectangular channel becomes plugged, the whole channel is blocked out. If any section of the face of the honeycomb becomes blinded with unburned paper or metal foil, that much of the honeycomb is blocked out. When this blockage occurs, carbon monoxide tends to become trapped in the stove, causing a potentially dangerous condition. It would be advantageous to display the catalytic surface in continuous slots instead of in rectangular channels. If the mouth of a slot becomes partly obstructed, flue gas can flow around the obstruction and enter the slot.
The chemical reaction whereby creosote vapor, which is not yet condensed to make smoke, is catalyzed and burned starts at about 500.degree. F. Below this temperature, the catalytic combustion is quenched and creosote vapor passes through burner into the chimney. When the fire is burning low, it is often difficult to keep the catalyst hot enough to sustain the catalytic combustion. One object of this invention is to provide a creosote burner that remains hot and active when the fire is low.